Copying lathe



April 28, 1925. 1,535,708

J. A. R. BENNET comma LATHE Filed April 28. 1923 3 Sheets-Sheet 1 [five/72am J. A. R. BENNE T COPYING LATHE 7 Filed April 2a. 1925 3 Sheets-Sheet 2' April 28, 1925. 1,535,708

J. A. R. BENNET COPYING LATHE Filed April 28, 1923 3 Sheets-Sheet 5 April 28, 1925. 1,535,708

JnI/eniaz; cZ/ZEBenneZ n a r) Patented Apr. 28, 1925.

UNITED STATES,

JULES AXEL RUE-GER BENNET, 0F LU'ND, SWEDEN.

COPYING LATHE.

Application filed Apri 28, R23. Serial No. 635,360.

To 11/! HltOl/l it may concern:

3e it known that l, Ji'iins Axial. RUTGER unwar a citizen of to wedei'i. resident of lluud. in the county of Malmohus, Sweden, have invented certain new and useful Improvements in Copying Lathes, of which the 't'ollowing is a specification.

This invention relates to improvements in copying lathes tor prod ucing turned articles that must be given a very exact circumference by using a copy or former in such a way that said circumference exactly corresponds to the copy or former used. for instance in turning of piston rings or the like. Hitherto in such turning a guide pin con nected with the cross slide of the saddle has usually been pressed positivetv against the tormer or copy fixed in achuck or tastened in a similar manner in such a way that the cross slide with the turning tool will be moved inwards or outwards during the rot-ation of the copy. Such devices, however, are atl'ected with the disadvantage that the cross slide and the turning tool do not positively and exactly follow the movements of the circumterence ot the copyor former on account of the inertia of the moving parts and the play resulting theretron'i and from other causes. this being a considerable drawback when it is the question of producing work of precision and thus also it impossible to use other than extremely low velocities when turning. This is also the case when a roller used for guiding the tool which roller is running in a groove in the former. In order to make it possible forthe roller treely to rotate it must rest only against one side of the groove in order not to be prevented from rotating, and therefore a certain play must be provided between the roller and the groove, so that an exact co -)yijng cannot be attained, irrespective of the fact that this defect will be increased gradually by wear of the groove and the roller.

The use of two guiding surfaces or form ers is already known as well as of two rollers one of which is pressed against one of the formers and the other roller against the other former, but these two rollers are mounted on a common axis and act in the same way and with the same drawbacks stated above. i\;'[oreover the latter device has for its purpose to produce surfaces of rotation and not in the same way as the present invention to turn non-circular surfaces such as piston rings.

It is also already known to change the ratio of gear of levers for the production of pieces of work of different sizes by using one and the same former or copy.

These disadvantages are done away with by the present invention by using an auxiliary or a so called counter-former guiding the movements of the cross slide and the tool duringthe turning together with the mainforiner from and towards the piece of work in such a 'way'that the greatest accuracy in shaping the piece of work in conformity to the used it'ormer may be obtained in an extremely simple manner. In this way the very great advantage is gained that in shaping the piece of work the cutting speed may be increased to the highest permissible for the turning tool and the material of the piece of work without altecting the exactitude of the shaping in any way.

In the accompanying drawing Fig. 1 is an end view of a machine constructed in accordance with the present invention. Fig. 2 is vertical section through a lathe bed having the new apparatus mounted thereon in a form different from the one shown in Fig. I. Fig. dis a similar section in two different planes to the right and left in the figure. Fig. L t is a plan view of the lathe. Figs. 5 and 6 are views in two different planes of a constructional detail.

For the-purposes of the present invention, it will be assumed that a perfectly correct main former has been provided and with such main former as the guide a similar counter former has been formed. The main former l and the counter former 7 are indicated on the drawings.

patter giving the counter-tornier 7 its proper circumference dependent ol' the main-former in any other suitable way it may be placed in a. chuck or a driving plate of a lathe together with the main-former without changing its position in relation to the latter. and in such a way that its centre O (Fig. 3) coincides with the axis of the spindle of the lathe. The cross slide 18 ot the lathe saddle 17 carries two arms 19 and 20 and on the ends of these arms rollers 21 and are provided one of which 21, is running along the circumference of the counter-former 7 and the other alone the circun'iterence of the main-former 1 in tlldlllCtl'lt'ttl opposition to the first mentioned roller when rotating the formers. The arms and it) are adjustable in the longitudinal direction of the cross slide 18 and may be fastened in such a way that each of the rollers 2i and 22 is held againstv its former, as shown on the drawing. During the rotation of the spindle of the lathe the cross slide lo thus will move to and fro because it is displaced in one direction by the inain-forn'ier and in the other direction by the counterfornier. During this movement the rollers 21 and 2:2 will always simultaneously rest against the edges of their formers without any play whatever as is the case when weights, springs or other devices necessary for the movements of the cross slide are used and only one former. The arms 15) and it) may oi course be locked in right po sition by any suitable devices. fly the movements of the tross slide caused by the formers the tool worlt'ing at the piece of work for instance a piston ring, will of course be moved in a similar way so that the piece of worlt is given a circumference exactly corresponding to the main former.

Another form of the invention is shown in Figs. l to b. It is not necessary that the points of contact between the rollers 2i and 22 and the formers T and l are exactly opposite each other on a diameter through the centre of the spindle of the lathe, as shown in Fig. 3, as they also may be arranged in some other way forming a more suitable form of the invention for practical use. it is evident that also when the two formers are turned a tertain angle in relation to each other and thereafter bolted together, a correspoi'iding movement may be imparted to the cross slide with ashorter although always constant distance between the two rollers 2i and 22 running on the formers, it these rollers are adjusted to such a distance in relation to *ach other that one of them Ll. in contact with the highest point it} on the counter-forn1er 7 when the other roller 22 is in contact with the lowest point 15 on the main-former 1. Also in this case the. sum of the distances between the centre of rotation O and the points of contact of the two rollers is always one and the same. In this case the rollers are carried by the upper ends of two double armed levers 25 inountetil in bearings 2 fastened to the fast head stock of the lathe. The lower arms of the levers 25 are pivotally connected with each other by n'ieans of a rod 26. The length of this rod 26 corresponds to the distance. between the fulcrums of the levers so that a parallelogram is formed whereby the stun of the distances between the centre of the spindle of the lathe and the axis of the roll ers 21 and 22 always is the same. It is ad vantageous to provide. the rod 22 with a turn-buckle 2? for the purpose of adjusting the length of the rod. The levers 25 are mounted in the bearings 23 by means of hollow journals 2S fastened on the lovers and in which horizontal shafts 20 are keyed The other end of each shaft rests in bearings 30 (Figs. 5 and ti) on the saddle 17. ()n the shafts 29 vertical arms 32 provided with a longitudinal slot 31 are fastened in front of the bearings 30. An adjustable carrier 33 is made to slide in said arms and to be fastened to the same. The carrier 5 may be locked in its tiil'l'erent positions by means of a nut 3i and on the side most remote from the arm 52 provided with a pin 35 engaging in a guide-way so on the cross slide i8. 'lhus when the main-former l. and the counter-former T rotate the levers 25 and thereby also the shafts 2!) and the arms :52 are turned forwards and backwards, whereby the carrier '33 by means of the pin 35 engaging in the guide-way 36 moves the cross slide lb forwards and backwards in such a way that the turning tool l3 will be moved perfectly uniformly with the rollers 21 and 22 and the piece of work is given a circumference that is entirely determined by the main-former 1. By the movement of the carrier 53 in the slot of the arm 32 and its locking in different positions various ratios of gear may be obtaineo, so that pieces of work of different sizes or diameters may be manufactured by using one and the same main-former and counter-former. The feeding slide 37. is carried by the cross slide 18 and carries the top slide 58 with the tool holder 35). The guide-way 36 fastened on the cross slide 18 may be provided with a special adjusting device in order to eliminate eventual play between the guide and the pin 35. This may be done by means of a bolt passing through a flange ll on the giii lo and an eye 12 on the cross slide.

it is obvious that the various details of the apparatus described above can be carried out in different ways without (.ligi'essing from the spirit of the invention.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States,

l. A copying lathe comprising a main former, a guiding member cooperating therewith a counterformer, a second gu1d ing member cooperating with the count*rion double arm levers pivotally mounted on the fast head stock of the lathe for supporting the guiding members, an adjustable member connecting said levers, and means fixed to the levers for transmitting movement to the cross slide of the lathe.

2. A copying lathe, comprising a main former and a counter-former, double arm levers, an adjustable member connecting said levers a guiding member carried by each lever and cooperating with a partieu lar former, said guiding members being u1ntormly movable, the sum of the distances between the axis of the lathe spindle and the axis of the guidii'ig members being always constant during the turning of the levers, a head stock for the lathe. a cross slide for the lathe. double arm levers mounted on shafts jonrnalled in bearings on the fast head stock of the lathe for supporting the guiding members, arms carried by said shafts for transmitting movement to the cross slide of the lathe, carriers in guideways in said cross slide, and means for adjustably securing said aims to said carriers.

3. A copying lathe, comprising a main former and a cou11ter-':t'or1ner, the latter be ing turned in relation to the former through an angle less than 180. and guiding members cooperating with the respective tormers at points which are not diametrically opposed, the cou11tertor1ner having a form in such relation to the form of the main former that the sum of the distances between the points of contacts of the guiding members and formers and the axis of rotation is always constant.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

JULES AXEL RTTTGER BENNET. Witnesses Euro Enrossox. G. Pmnnssox. 

